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Technological points in carding:
There are two types of feeding to the cards-
- Feeding material in the form of scutcher lap
- Flock feed system (flocks are transported pneumatically)
Lap feeding
- Linear density of the lap is very good and it is easier to maintain (uniformity) the whole installation is very flexible deviations in card output will be nil, as laps can be rejected auto-levelers are not required, hence investment cost and maintenance cost is less transportation of lap needs more manual efforts (more labour) lap run out is an additional source of fault, as it should be replaced by a new lap.
- More good fibre loss during lap change.
- More load on the taker-in, as laps are heavily compressed.
Flock feeding
- High performance in carding due to high degree of openness of feed web labour requirement is less due to no lap transportation and lap change in cards flock feeding is the only solution for high production cards linear density of the web fed to the card is not as good as lap installation is not flexible auto-leveler is a must, hence investment cost and maintenance cost is more.
- Rieter has developed a “unidirectional feed system” where the two feed devices(feed roller and feed plate are oppositely arranged when compared with the conventional system. i.e. the cylinder is located below and the plate is pressed against the cylinder by spring force. Owing to the direction of feed roller, the fibre batt runs downwards without diversion directly into the teeth of the taker-in (licker-in) which results in gentle fibre treatment. This helps to reduce faults in the yarn.
- The purpose if the taker-in is to pluck finely opened flocks out of the feed batt, to lead them over the dirt eliminating parts like mote knives, combing segment and waste plates, and then to deliver the fibres to the main cylinder. In high production cards the rotational speed ranges from 700-1400.
Card feeding:
Card feeding is of two types;
- Lap feed (conventional).
- Chute feed or Flock feed (modern).
- Single System
- Double System
Basic elements of chute feed system:
- Conveyer system.
- Proper control of air pressure.
- A mechanism to feed the material at uniform weight per unit length.
- A delivery system to feed material to card feed roller.
- A sensing mechanism to keep a certain amount of material as reserve.
Advantage of lap feeding:
- Linear density of the lap is very good and it is easier to maintain (Uniformity).
- The whole installation is very flexible.
- Auto levelers are not required; hence investment cost & maintains cost is less.
- Transportation of lap needs more manual efforts.
Disadvantage of lap feeding:
- Deviations in card output will be nil as laps can be rejected.
- Lap run out in an additional source of fault as it should be replaced by a new lap.
- More good fibre loss during lap change.
- More load on the taker-in as lap is heavily compressed.
Advantage of chute or flock feeding:
- High performance in carding due to high degree of openness of feed web.
- Labors requirement is less due to no lap transportation & lap change in cards.
- Flock feeding is the only solution for high production cards.
Disadvantage of chute or flock feeding:
- Auto leveler is a must; hence investment cost & maintains cost is more.
- Linear density of the web fed to the card is not as good as lap.
- Installation is not flexible.
